Sahih Bukhari
Merits of the Helpers in Madinah (Ansaar)
Volume: 005 / Book Number: 058 / Hadith Number: 174
Narrated Sa'id bin Al-Musaiyab's grand-father:
In the pre-lslamic period of ignorance a flood of rain came and filled the valley in between the two mountains (around the Ka'ba)......